EP4695318A1

EP4695318A1 - Methods of preparing coated substrates and non-aqueous, curable film-forming compositions used therefor

Info

Publication number: EP4695318A1
Application number: EP24708080.7A
Authority: EP
Inventors: David Joseph FORTMAN; David N. Walters
Original assignee: PPG Industries Ohio Inc
Current assignee: PPG Industries Ohio Inc
Priority date: 2023-04-10
Filing date: 2024-01-23
Publication date: 2026-02-18
Also published as: KR20250172623A; WO2024215380A1; AU2024249933A1; CN121002090A

Abstract

The present disclosure is directed to non-aqueous, curable film-forming compositions comprising: a) an anhydride functional compound; b) an aziridine functional compound; and c) a hydroxyl functional compound different from a) and b) and having at least two hydroxyl functional groups. The present disclosure is further directed to methods of preparing coated substrates with these compositions, an exemplary method comprising: (A) optionally applying a primary film-forming composition to at least a portion of a surface of the substrate to form a first coating; (B) applying the curable film-forming composition directly to at least a portion of a surface of the substrate or to at least a portion of the first coating formed in step (A) to form a coated substrate; and (C) subjecting the coated substrate to curing conditions, whereby the curable film-forming composition undergoes multiple cure reactions.

Description

METHODS OF PREPARING COATED SUBSTRATES AND NONAQUEOUS, CURABLE FILM-FORMING COMPOSITIONS USED THEREFOR

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001] This invention was developed with support by the United States Government under contract AF UDRI Advanced Performance Materials awarded by the U.S. Air Force Research Laboratory (AFRL). The United States Government may have certain rights in the invention.

FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to non-aqueous, curable film-forming compositions capable of undergoing multiple cure reactions, and methods of preparing coated substrates with them.

BACKGROUND

[0003] Two-package (“2K”) polyurethane coatings have become the industry standard in many aerospace, industrial, and automotive refinish applications for their combination of ambient or low temperature curing, durability, and weatherability. These coatings typically rely on polyfunctional isocyanate crosslinkers which can present concerns with user sensitization. As a result, isocyanates are becoming increasingly regulated because they are believed to pose environmental health and safety risks.

[0004] The coatings industry has taken an interest in developing nonisocyanate coatings that are comparable in performance to polyurethane systems. However, developing novel, safer compositions with properties competitive with isocyanate-cured coatings is an ongoing challenge. Nonisocyanate crosslinkers for existing hydroxyl functional resins which offer similar performance attributes would be of particular value in multiple end-use applications.

[0005] It would be desirable to provide curable film-forming compositions that undergo isocyanate-free cure chemistries, and that proceed at ambient conditions or low temperatures as defined below to yield coatings with properties comparable to polyurethane coatings.

SUMMARY

[0006] The present disclosure is directed to non-aqueous, curable film-forming compositions comprising: a) an anhydride functional compound; b) an aziridine functional compound; and c) a hydroxyl functional compound different from a) and b) and having at least two hydroxyl functional groups. The present disclosure is further directed to methods of preparing coated substrates with these compositions, an exemplary method comprising: (A) optionally applying a primary film-forming composition to at least a portion of a surface of the substrate to form a first coating; (B) applying the curable film-forming composition directly to at least a portion of a surface of the substrate or to at least a portion of the first coating formed in step (A) to form a coated substrate; and (C) subjecting the coated substrate to curing conditions, whereby the curable film-forming composition undergoes multiple cure reactions.

DETAILED DESCRIPTION

[0007] Other than in any operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0008] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0009] Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

[0010] As used in this specification and the appended claims, the articles "a," "an," and "the" include plural referents unless expressly and unequivocally limited to one referent.

[0011] The various examples presented herein are each understood to be nonlimiting with respect to the scope of the disclosure.

[0012] As used in the following description and claims, the following terms have the meanings indicated below:

[0013] The term "curable", as used for example in connection with a curable composition, means that the indicated composition is polymerizable or cross linkable through functional groups, e.g., by means that include, but are not limited to, thermal (including ambient cure) and/or catalytic exposure. Ambient temperature usually ranges from 60 to 90°F (15.6 to 32.2°C), such as a typical room temperature, 72°F (22.2°C).

[0014] The term “cure”, “cured” or similar terms, as used in connection with a cured or curable composition, e.g., a “cured composition” of some specific description, means that at least a portion of the polymerizable and/or crosslinkable components that form the curable composition is polymerized and/or crosslinked through reactive functional groups, to the extent that a cured film prepared from the composition demonstrates no damage from at least 50 methylethyl ketone (MEK) double rubs according to ASTM D5402-19. The test method may be performed, for example, using the specified cheesecloth or another suitable cloth such as a Wypall X80 towel available from Kimberly Clark Corporation. Additionally, curing of a polymerizable composition refers to subjecting said composition to curing conditions such as but not limited to thermal curing, leading to the reaction of the reactive functional groups of the composition, and resulting in polymerization and formation of a polymerizate. When a polymerizable composition is subjected to curing conditions, following polymerization and after reaction of most of the reactive groups occurs, the rate of reaction of the remaining unreacted reactive groups becomes progressively slower. The polymerizable composition can be subjected to curing conditions until it is at least partially cured. The term “at least partially cured” means subjecting the polymerizable composition to curing conditions, wherein reaction of at least a portion (e. g., at least 5 percent) of the reactive groups of the composition occurs, to form a polymerizate. The polymerizable composition can also be subjected to curing conditions such that a complete cure is attained (for example, greater than 50 percent of reactive groups have reacted) and wherein further curing results in no further improvement in polymer properties, such as hardness.

[0015] The term “reactive” refers to a functional group capable of undergoing a chemical reaction with itself and/or other functional groups spontaneously or upon the application of heat or in the presence of a catalyst or by any other means known to those skilled in the art. Note that the phrase “and/or” when used in a list is meant to encompass alternative embodiments including each individual component in the list as well as any combination of components. For example, the list “A, B, and/or C” is meant to encompass seven separate embodiments that include A, or B, or C, or A + B, or A + C, or B + C, or A + B + C.

[0016] The curable film-forming composition of the present disclosure is nonaqueous. By “non-aqueous” is meant that the composition may be a liquid that is solventborne or up to 100% solids, or the composition may be a solid particulate (i. e., “powder”) composition. In a solventborne composition, solid components are dispersed and/or dissolved in an organic solvent medium. As used herein, an “organic solvent medium” and “solventborne” refer to a liquid medium comprising at least 50 weight % organic solvent, based on the total weight of the liquid medium. Such liquid mediums can for example comprise at least 60 weight % organic solvent, or at least 70 weight % organic solvent, or at least 80 weight % organic solvent, or at least 90 weight % organic solvent, or at least 95% organic solvent, based on the total weight of the liquid medium. The composition may comprise up to 100% solids. As such, components may, for example, be dissolved and/or dispersed in an organic medium that comprises in whole or in part an organic reactive diluent. In some cases, the medium may include water, and the water may react with the anhydride functional groups and/or hydrolyzable groups in the curable film-forming composition. The composition may also be substantially free, essentially free, or completely free of water. The terms “substantially free of [a given compound]” means that the composition contains less than 1000 parts per million (ppm) of the given compound; “essentially free of [a given compound]” means that the composition contains less than 100 ppm of the given compound; and “completely free of [a given compound]” means that the composition contains less than 20 parts per billion (ppb) of the given compound. The weight is based on the total weight of the composition.

[0017] As noted, the composition may contain organic solvents as necessary for the purposes of formulation. Such solvents include ketones, such as methyl amyl ketone and methyl isobutyl ketone; aromatic hydrocarbons, such as xylene; glycol ethers, such as propylene glycol methyl ether, propylene glycol monopropyl ether, ethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, and ethylene glycol monohexyl ether; and/or esters such as 2-butoxyethyl ester of acetic acid and propylene glycol monomethyl ether acetate. Other solvents including alcohols, such as butanol, may be suitable and may additionally serve as scavengers or reactive diluents, depending on the reactivity of the hydroxyl group (i. e., primary vs. secondary vs. tertiary). Mixtures of any of the foregoing solvents may also be used.

[0018] The curable film-forming composition comprises: (a) an anhydride functional compound, having at least one anhydride functional group. The anhydride functional compound may comprise a “small molecule” (i.e., a compound having a molecular weight less than 1000 Da, such as less than 700 Da, or less than 500 Da, and at least 98 Da, or at least 125 Da, or at least 200 Da, as determined by mass spectroscopy). Monomeric compounds such as anhydrides with molecular weights in the range of 98 to 400 Da are typical. Examples include one or more of maleic anhydride, hexahydrophthalic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, including alkyl-substituted anhydrides such as methyl hexahydrophthalic anhydride and methyl succinic anhydride. Typically, the anhydride functional group is cyclic, but a non-cyclic anhydride functional compound generated from polycondensation of multifunctional acids may be used, such as in combination with a cyclic anhydride compound. In certain examples, the anhydride functional compound (a) does not contain hydroxyl functional groups, and the curable film-forming composition is substantially free, essentially free, or completely free of anhydride functional compounds that contain hydroxyl functional groups.

[0019] The anhydride functional compound (a) in the curable film-forming compositions may additionally or alternatively comprise an anhydride- containing polymer. By “polymer” is meant a polymer including homopolymers and copolymers, and oligomers. For example, the anhydride functional compound (a) may comprise an addition polymer, prepared from ethylenically unsaturated monomers or polymeric compounds such as anhydride functional polymers having number average molecular weights up to 1 ,000,000 Da such as in the range of at least 1 ,000 Da, or at least 50,000 Da, or at least 100,000 Da, to at most 1 ,000,000 Da, or at most 500,000 Da, or at most 250,000 Da, as measured using gel permeation chromatography with a polystyrene standard.

[0020] Ethylenically unsaturated anhydrides useful in the preparation of an anhydride-containing addition polymer include, for instance, itaconic anhydride, maleic anhydride, isobutenyl succinic anhydride and the like. Typically, the ethylenically unsaturated anhydride may be present in the reaction mixture used to prepare the addition polymer in amounts of at least 1 percent by weight and up to 50 percent by weight, such as 5 to 40 percent by weight, based on total weight of monomers used to prepare the polymer.

[0021] The ethylenically unsaturated anhydride may be polymerized with one or more other ethylenically unsaturated monomers not having an anhydride moiety including vinyl ethers, vinyl esters, 1 -octene, 1 -butene, isobutylene, styrene, 2-methyl styrene, and the like. In some examples, the ethylenically unsaturated anhydride may be polymerized with a vinylalkoxysilane, such as vinyltrimethoxysilane or vinyltriethoxysilane. [0022] Other examples of suitable anhydride-containing polymers are, for instance, anhydride-containing (meth)acrylic polymers such as (meth)acrylic polymers having at least two anhydride groups. Typically, the anhydride- containing polymers such as anhydride-containing (meth)acrylic polymers have a number average molecular weight of 1 ,000 to 1 ,000,000 Da as measured using gel permeation chromatography with a polystyrene standard. The term “(meth)acrylate” is meant to encompass acrylate and/or methacrylate molecular structures where they exist.

[0023] An exemplary anhydride-containing (meth)acrylic polymer can be prepared by various means known to one skilled in the art such as conventional free-radical or controlled free-radical polymerization. For example, an anhydride-containing (meth)acrylic polymer can be prepared by conventional techniques in which the monomers, solvent, and conventional initiators such as t-butyl perbenzoate are charged into a polymerization vessel and heated to between 75^s and 200^sC for about 0.5 to 6 hours to form the polymer.

[0024] An anhydride-containing (meth)acrylic polymer can be formed by copolymerizing monomers selected from alkyl methacrylates, alkyl acrylates or mixtures thereof, where the alkyl groups can have 1 -12 carbon atoms, with ethylenically unsaturated anhydrides (or ethylenically unsaturated dicarboxylic acids which are converted to the acid anhydride during or after the polymerization).

[0025] Typical alkyl acrylates and methacrylates that can be used to form an anhydride-containing (meth)acrylic polymer may include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, isobornyl acrylate, isobornyl methacrylate, and the like. Other ethylenically unsaturated monomers, i.e. ethylenically unsaturated monomers different from alkyl (meth)acrylates and ethylenically unsaturated anhydrides (or ethylenically unsaturated dicarboxylic acids which are converted to the acid anhydride during or after the polymerization), such as styrene, 2-methyl styrene, (meth)acrylonitrile, (meth)acrylamide, (meth)acrylo alkoxy silanes and (meth)acrylic acid may also be used. Mixtures of two or more of the above monomers are often used. The non-anhydride monomers are typically present in amounts of up to 99 percent by weight, such as 50 to 95 percent by weight, based on the total weight of the monomers used to prepare the polymer.

[0026] The anhydride functional compound (a) is present in the curable filmforming composition in an amount of at least 5, such as at least 10, or at least 20 percent by weight, based on the total weight of resin solids in the curable film-forming composition. The anhydride functional compound (a) is present in the curable film-forming composition in an amount of at most 75, such as at most 60, or at most 50 percent by weight, based on the total weight of resin solids in the curable film-forming composition. For example, the anhydride functional compound (a) may be present in the curable film-forming composition in an amount of 5 to 75 percent by weight, or 5 to 60 percent by weight, or 5 to 50 percent by weight, or 10 to 75 percent by weight, or 10 to 60 percent by weight, or 10 to 50 percent by weight, or 20 to 75 percent by weight, or 20 to 60 percent by weight, or 20 to 50 percent by weight.

[0027] The curable film-forming composition further comprises (b) an aziridine functional compound. Examples of suitable aziridine functional compounds include polyfunctional aziridines such as those disclosed in W02020/020714A1 , oligomeric or small molecule polyfunctional aziridines such as PZ-28 and PZ-33 Polyfunctional Aziridine available from PolyAziridine LLC or Crosslinker CX-100, available from Covestro. Further exemplary aziridines include polymeric compounds such as NeoAdd® PAX-521 or NeoAdd® PAX-523, available from Covestro. Additional suitable aziridine functional molecules may be generated, for example, by reaction of 1 - aziridineethanol with a polyfunctional isocyanate or by reaction of ethyleneimine with a polyfunctional acrylate.

[0028] The aziridine functional compound (b) is present in the curable filmforming composition in an amount of at least 5, such as at least 10, or at least 20 percent by weight, based on the total weight of resin solids in the curable film-forming composition. The aziridine functional compound a) is present in the curable film-forming composition in an amount of at most 75, such as at most 60, or at most 50 percent by weight, based on the total weight of resin solids in the curable film-forming composition. For example, the anhydride functional compound a) may be present in the curable film-forming composition in an amount of 5 to 75 percent by weight, or 5 to 60 percent by weight, or 5 to 50 percent by weight, or 10 to 75 percent by weight, or 10 to 60 percent by weight, or 10 to 50 percent by weight, or 20 to 75 percent by weight, or 20 to 60 percent by weight, or 20 to 50 percent by weight.

[0029] The curable film-forming composition further comprises (c) a hydroxyl functional compound different from (a) and (b) and having at least two hydroxyl functional groups. After application of the curable film-forming composition to a substrate to form a coated substrate, and upon subjecting the coated substrate to curing conditions, the curable film-forming composition undergoes multiple cure reactions. While not intending to be bound by theory, it is believed the multiple cure reactions may comprise i) reaction of the anhydride with hydroxyl functional groups to form ester functional groups and carboxylic acid functional groups, and/or hydrolysis of the anhydride by atmospheric humidity to form carboxylic acid functional groups; and ii) reaction of the carboxylic acid functional groups with the aziridine functional compound (b).

[0030] Compounds (a), (b), and (c) are not only different, but in certain examples, (a) may be free of aziridine and hydroxyl functionality, (b) may be free of anhydride and hydroxyl functionality and (c) may be free of anhydride and aziridine functionality.

[0031] Suitable hydroxyl functional compounds (c) include polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, 1 ,6-hexylene glycol, neopentyl glycol, diethylene glycol, glycerol, trimethylol propane, and pentaerythritol. More often the hydroxyl functional compounds (c) are oligomers or polymers, such as acrylic polyols, polyester polyols, and/or polyurethane polyols.

[0032] Suitable acrylic polyols include copolymers of one or more alkyl esters of acrylic acid or methacrylic acid, optionally together with one or more other polymerizable ethylenically unsaturated monomers. Useful alkyl esters of acrylic acid or methacrylic acid include aliphatic alkyl esters containing from 1 to 30, and often 4 to 18 carbon atoms in the alkyl group. Non-limiting examples include methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethyl acrylate, butyl acrylate, and 2-ethyl hexyl acrylate. Suitable other copolymerizable ethylenically unsaturated monomers include vinyl aromatic compounds such as styrene and vinyl toluene; nitriles such as acrylonitrile and methacrylonitrile; vinyl and vinylidene halides such as vinyl chloride and vinylidene fluoride and vinyl esters such as vinyl acetate.

[0033] The acrylic copolymer includes hydroxyl functional groups, which are often incorporated into the polymer by including one or more hydroxyl functional monomers in the reactants used to produce the copolymer. Useful hydroxyl functional monomers include hydroxyalkyl acrylates and methacrylates, typically having 2 to 4 carbon atoms in the hydroxyalkyl group, such as hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxy functional adducts of caprolactone and hydroxyalkyl acrylates, and corresponding methacrylates, as well as the hydroxy ester functional monomers described below.

[0034] Hydroxy ester functional monomers can be prepared from either i) ethylenically unsaturated, epoxy functional monomers and carboxylic acids having from about 13 to about 20 carbon atoms, or from ii) ethylenically unsaturated acid functional monomers and epoxy compounds containing at least 5 carbon atoms which are not polymerizable with the ethylenically unsaturated acid functional monomer.

[0035] Useful ethylenically unsaturated, epoxy functional monomers used to prepare the hydroxy ester functional monomers include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether, 1 :1 (molar) adducts of ethylenically unsaturated monoisocyanates with hydroxy functional monoepoxides such as glycidol, and glycidyl esters of polymerizable polycarboxylic acids such as maleic acid. Examples of carboxylic acids include saturated monocarboxylic acids such as isostearic acid and aromatic unsaturated carboxylic acids.

[0036] Useful ethylenically unsaturated acid functional monomers used to prepare the hydroxy ester functional monomers include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid; dicarboxylic acids such as itaconic acid, maleic acid and fumaric acid; and monoesters of dicarboxylic acids such as monobutyl maleate and monobutyl itaconate. The ethylenically unsaturated acid functional monomer and epoxy compound are typically reacted in a 1 :1 equivalent ratio. When an ethylenically unsaturated acid functional monomer is used to prepare the hydroxy ester functional monomers, the epoxy compound does not contain ethylenic unsaturation that would participate in free radical-initiated polymerization with the unsaturated acid functional monomer. Useful epoxy compounds include 1 ,2-pentene oxide, styrene oxide and glycidyl esters or ethers, often containing from 8 to 30 carbon atoms, such as butyl glycidyl ether, octyl glycidyl ether, phenyl glycidyl ether and para-(tertiary butyl) phenyl glycidyl ether. Particular glycidyl esters include those of the structure:

O where R is a hydrocarbon radical containing from about 4 to about 26 carbon atoms. Typically, R is a branched hydrocarbon group such as neopentanoate, neoheptanoate or neodecanoate. Suitable glycidyl esters of carboxylic acids include CARDURA E10P, which is commercially available from Hexion.

[0037] The preparation of an exemplary polymeric acrylic polyol using hydroxybutyl acrylate is demonstrated in the Examples below. One skilled in the art would appreciate that one or more of the afore-mentioned or other ethylenically unsaturated monomers would be suitable for reaction with one or more ethylenically unsaturated hydroxyl functional monomers in a similar fashion to prepare a polymeric acrylic polyol for use as the hydroxyl functional compound (c).

[0038] The resulting acrylic polymer may have a hydroxyl value of at least 25, or at least 50, in some cases at least 100, in other cases at least 150. Additionally, the acrylic polymer may have a hydroxyl value of not more than 250, in some cases not more than 225, in other cases not more than 200, based on the total weight of the acrylic polymer. The hydroxyl value may be determined, for example, using Method A or B of ASTM E222-10 (2010). The hydroxyl value of the acrylic polymer may be any value or any range of values inclusive of those stated above. For example, the resulting acrylic polymer may have a hydroxyl value of 25 to 250 mg KOH/g, or 50 to 225 mg KOH/g, or 50 to 200 mg KOH/g, or 100 to 250 mg KOH/g, or 100 to 225 mg KOH/g, or 100 to 200 mg KOH/g, or 150 to 250 mg KOH/g, or 150 to 225 mg KOH/g, or 150 to 200 mg KOH/g, based on the total mass of the acrylic polymer, including any solvents that are present.

[0039] The hydroxyl functional compound (c) may additionally or alternatively comprise a polyester polyol. Such polymers may be prepared in a known manner by condensation of polyhydric alcohols and polycarboxylic acids, while using the polyhydric alcohols in stoichiometric excess. Suitable polyhydric alcohols include, but are not limited to, ethylene glycol, propylene glycol, butylene glycol, 1 ,6-hexylene glycol, neopentyl glycol, diethylene glycol, glycerol, trimethylol propane, and pentaerythritol. Suitable polycarboxylic acids include, but are not limited to, succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and trimellitic acid. Besides the polycarboxylic acids mentioned above, functional equivalents of the acids such as anhydrides where they exist or lower alkyl esters of the acids such as the methyl esters may be used.

[0040] Polyurethane polyols may additionally or alternatively be used as the hydroxyl functional compound (c) in the curable film-forming composition. Among the polyurethanes which can be used are polymeric polyols which generally are prepared by reacting a polyol such as those mentioned above, or a different polyol such as a polyether polyol with a polyisocyanate such that the OH/NCO equivalent ratio is greater than 1 :1 and free hydroxyl groups are present in the product. The organic polyisocyanate which is used to prepare the polyurethane polyol can be an aliphatic or an aromatic polyisocyanate or a mixture of the two. Diisocyanates include toluene diisocyanate, 4,4'-methylene-bis(cyclohexyl isocyanate), isophorone diisocyanate, an isomeric mixture of 2,2,4- and 2,4,4-trimethyl hexamethylene diisocyanate, 1 ,6-hexamethylene diisocyanate, tetramethyl xylylene diisocyanate and/or 4,4'-diphenylmethylene diisocyanate. Biurets of any suitable diisocyanate including 1 ,4-tetramethylene diisocyanate and 1 ,6-hexamethylene diisocyanate may be used. Also, biurets of cycloaliphatic diisocyanates such as isophorone diisocyanate and 4,4'-methylene-bis-(cyclohexyl isocyanate) can be employed. Examples of suitable aralkyl diisocyanates from which biurets may be prepared are meta-xylylene diisocyanate and a,a,a',a’- tetramethylmeta-xylylene diisocyanate.

[0041] Trifunctional isocyanates may also be used to prepare the polyurethane polyol, for example, trimers of isophorone diisocyanate, triisocyanato nonane, triphenylmethane triisocyanate, 1 ,3,5-benzene triisocyanate, 2,4,6-toluene triisocyanate, an adduct of trimethylol and tetramethyl xylene diisocyanate sold under the name CYTHANE 3160 by CYTEC Industries, and DESMODUR N 3390, which is the isocyanurate of hexamethylene diisocyanate, available from Bayer Corporation. Other polyisocyanates include trimers of diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate. DESMODUR Z 4470 BA, an aliphatic polyisocyanate based on isophorone diisocyanate available from Bayer Corporation, is also suitable.

[0042] The hydroxyl functional compound (c) may be present in the curable film-forming composition in an amount of at least 10, such as at least 20, or least 35, or at least 40, or at least 45 percent by weight, based on the total weight of resin solids in the curable film-forming composition. The hydroxyl functional compound (c) may be present in the curable film-forming composition in an amount of at most 90, such as at most 80, or at most 70 percent by weight, based on the total weight of resin solids in the curable film-forming composition. For example, the hydroxyl functional compound (c) may be present in the curable film-forming composition in an amount of 10 to 90 percent by weight, or 10 to 80 percent by weight, or 10 to 70 percent by weight, or 20 to 90 percent by weight, or 20 to 80 percent by weight, or 20 to 70 percent by weight, or 35 to 90 percent by weight, or 35 to 80 percent by weight, or 35 to 70 percent by weight, or 40 to 90 percent by weight, or 40 to 80 percent by weight, or 40 to 70 percent by weight, or 45 to 90 percent by weight, or 45 to 80 percent by weight, or 45 to 70 percent by weight, based on the total weight of resin solids in the curable film-forming composition.

[0043] In certain examples, the curable film-forming composition further comprises hydrolyzable functional groups different from anhydride. By “hydrolyzable” is meant functional groups that may undergo hydrolysis in the presence of water molecules and subsequently condense, such as by self- condensation, to form crosslinks. The hydrolyzable functional groups typically comprise one or more of alkoxysilane (such as methoxysilane, ethoxysilane, and the like); acetoxysilane, ketoxime silane, silicates, including orthosilicates such as alkylorthosilicates; titanates such as tetraalkyl titanates; and zirconates such as tetraalkyl zirconates. Chelates of titanium, zirconium, and/or silicon are also suitable. The hydrolyzable functional groups may be present on the anhydride functional compound, the aziridine functional compound, the hydroxyl functional compound, and/or on a separate compound that is different from the anhydride functional compound, the aziridine functional compound, and the hydroxyl functional compound. For example, the hydrolyzable groups may be present only on the anhydride functional compound, only on the hydroxyl functional compound, only on the aziridine functional compound, only on the separate compound, or on two or more of the compounds.

[0044] Examples of anhydride functional compounds (a) that further comprise hydrolyzable functional groups include (3-trialkoxysilyl)propyl succinic anhydrides, such as (3-triethoxysilyl)propyl succinic anhydride and (3- trimethoxysilyl)propyl succinic anhydride. When the anhydride functional compound (a) comprises a polymer, hydrolyzable functional groups may be incorporated, for example, by including vinyl or (meth)acrylic monomers that contain hydrolyzable functional groups in the reaction mixture used to prepare the polymer. Examples of suitable silane functional monomers include vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxyethoxytris(trimethoxy) silane, 3-methacryloxypropyl tris-(2-methoxyethoxy) silane, and 3- (trimethoxysilyl)propyl methacrylate, available as SILQUEST A-174 from Momentive Performance Chemicals.

[0045] Aziridine compounds with hydrolyzable groups may be prepared, for example, by reacting a polyfunctional isocyanate with a mixture of aminosilane or mercaptosilane and 1 -aziridineethanol; or by reacting a polyfunctional acrylate with mixture of ethyleneimine and aminosilane or mercaptosilane.

[0046] Hydroxyl functional compounds (c) that further comprise hydrolyzable functional groups may be prepared, for example, by preparing an acrylic polyol as above with ethylenically unsaturated monomers comprising hydrolyzable groups such as any of those disclosed above. Alternatively, a polyol may be reacted in stoichiometric excess with an isocyanato silane.

[0047] As noted above, the hydrolyzable functional groups may be present additionally or alternatively on a separate compound that is different from the anhydride functional compound, the hydroxyl functional compound, and the aziridine functional compound. An exemplary compound having hydrolyzable functional groups may comprise urethane and/or urea linkages. Such a compound may be prepared from a reaction mixture comprising a polyisocyanate such as hexamethylene diisocyanate trimer and/or any of those disclosed above; a diol such as 1 ,6-hexanediol, ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, diethylene glycol, glycerol, trimethylol propane, and pentaerythritol; and an amino-functional alkoxysilane such as N- (n-butyl)-3-aminopropyltrimethoxysilane. One skilled in the art would appreciate that one or more of the afore-mentioned or other polyisocyanates would be suitable for reaction with one or more polyols and active hydrogen functional materials having hydrolyzable functional groups in a similar fashion to prepare a compound having hydrolyzable functional groups. In another example, the separate compound having hydrolyzable functional groups comprises an acrylic polymer having silane functional groups.

[0048] The curable film-forming compositions may further comprise a particulate filler. Examples of fillers that can be present include minerals such as barium sulfate, silica, including fumed silica and colloidal silica, alumina, colloidal alumina, titanium dioxide, zirconia, colloidal zirconia, clay, mica, dolomite, talc, magnesium carbonate, calcium carbonate, calcium sulfate, and the like. It is believed that the fillers, in combination with the resins in the composition, allow for useful rheological properties such as thixotropy. Fillers such as colloidal silica may also serve to enhance mar and scratch resistance. [0049] The film-forming composition can additionally include a variety of optional ingredients and/or additives that are somewhat dependent on the particular application of the curable composition, such as pigments or other colorants, reinforcements, thixotropes, accelerators, surfactants, plasticizers, extenders, stabilizers, corrosion inhibitors, diluents, hindered amine light stabilizers, UV light absorbers, adhesion promoters, and antioxidants. The curable film-forming composition may be a color coat or clear coat.

[0050] As noted above, the curable film-forming compositions disclosed herein can also include a colorant. As used herein, the term “colorant” means any substance that imparts color and/or other opacity and/or other visual effect to the composition. The colorant can be added to the coating in any suitable form, such as discrete particles, dispersions, solutions and/or flakes. A single colorant or a mixture of two or more colorants can be used in the curable filmforming compositions.

[0051] Example colorants include pigments, dyes and tints, such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA), as well as special effect compositions. A colorant can be organic or inorganic and can be agglomerated or non-agglomerated. Colorants can be incorporated into the coatings by grinding or simple mixing. Colorants can be incorporated by grinding into the coating by use of a grind vehicle, such as an acrylic grind vehicle, the use of which will be familiar to one skilled in the art.

[0052] Example pigments and/or pigment compositions include, but are not limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone, condensation, metal complex, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketo pyrrole pyrrole red (“DPPBO red”), titanium dioxide, carbon black and mixtures thereof. The terms “pigment” and “colored filler” can be used interchangeably.

[0053] As noted above, the colorant can be a pigment or dye in the form of a dispersion including, but not limited to, a nanoparticle dispersion. Nanoparticle dispersions can include one or more nanoparticle colorants and/or colorant particles that produce a desired visible color and/or opacity and/or visual effect. Nanoparticles can be produced by milling stock organic or inorganic pigments with grinding media having a particle size of less than 0.5 mm. Example nanoparticle dispersions and methods for making them are identified in U.S. Patent No. 6,875,800 B2. Nanoparticle dispersions can also be produced by crystallization, precipitation, gas phase condensation, and chemical attrition (i.e., partial dissolution). In order to minimize re-agglomeration of nanoparticles within the coating, a dispersion of resin-coated nanoparticles can be used. As used herein, a “dispersion of resin-coated nanoparticles” refers to a continuous phase in which is dispersed discreet “composite microparticles” that comprise a nanoparticle and a resin coating on the nanoparticle.

[0054] Example special effect compositions that may be used in the curable film-forming compositions include pigments and/or compositions that produce one or more appearance effects such as reflectance, pearlescence, metallic sheen, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, goniochromism and/or color-change. Additional special effect compositions can provide other perceptible properties, such as reflectivity, opacity or texture. In a non-limiting example, special effect compositions can produce a color shift, such that the color of the coating changes when the coating is viewed at different angles. Example color effect compositions are identified in U.S. Patent No. 6,894,086. Additional color effect compositions can include transparent coated mica and/or synthetic mica, coated silica, coated alumina, a transparent liquid crystal pigment, a liquid crystal coating, and/or any composition wherein interference results from a refractive index differential within the material and not because of the refractive index differential between the surface of the material and the air.

[0055] In certain non-limiting examples, a photosensitive composition and/or photochromic composition, which reversibly alters its color when exposed to one or more light sources, can be used in the curable film-forming composition. Photochromic and/or photosensitive compositions can be activated by exposure to radiation of a specified wavelength. When the composition becomes excited, the molecular structure is changed and the altered structure exhibits a new color that is different from the original color of the composition. When the exposure to radiation is removed, the photochromic and/or photosensitive composition can return to a state of rest, in which the original color of the composition returns. In one non-limiting example, the photochromic and/or photosensitive composition can be colorless in a non-excited state and exhibit a color in an excited state. Full color-change can appear within milliseconds to several minutes, such as from 20 seconds to 60 seconds. Example photochromic and/or photosensitive compositions include photochromic dyes.

[0056] In a non-limiting example, the photosensitive composition and/or photochromic composition can be associated with and/or at least partially bound to, such as by covalent bonding, a polymer and/or polymeric materials of a polymerizable component. In contrast to some coatings in which the photosensitive composition may migrate out of the coating and crystallize into the substrate, the photosensitive composition and/or photochromic composition associated with and/or at least partially bound to a polymer and/or polymerizable component in accordance with a non-limiting example of the present disclosure, have minimal migration out of the coating. Example photosensitive compositions and/or photochromic compositions and methods for making them are identified in U.S. Application Publication No. 2006/0014099.

[0057] In general, the colorant can be present in the curable film-forming composition in any amount sufficient to impart the desired property, visual and/or color effect. The colorant may comprise from 1 to 65 weight percent of the present compositions, such as from 3 to 40 weight percent or 5 to 35 weight percent, with weight percent based on the total weight of the compositions.

[0058] The curable compositions can be prepared as a one-package or multipackage such as a two-package composition, more often as a multi-package composition that may be curable at ambient temperature. Multi-package curable compositions are typically prepared by combining the ingredients immediately before use. The composition may further comprise a catalytic material, present in one or more of the packages or in a separate package. The hydrolyzable functional groups, when present, may be present on any of the compounds or on a separate compound, in one or more of the packages or in a separate package.

[0059] In a particular example, the curable film-forming composition comprises separate packages. For example, a first package may comprise the anhydride functional compound (a) and a second package may comprise the hydroxyl functional compound (c). The aziridine functional compound (b) may be present in the first and/or second package. When the curable film-forming composition further comprises (d) a catalytic material that catalyzes a chemical reaction between hydroxyl and anhydride functional groups, the catalyst (d) may be in the second package. Alternatively, the three components (a), (b), and (c) may be in each of three separate packages. When a separate compound having hydrolyzable functional groups, that is different from the anhydride functional compound (a), the aziridine functional compound (b), and the hydroxyl functional compound (c), is present in the curable film-forming composition, it may be present in one or more of the other packages or in its own package. The packages are separate from one another until immediately prior to application of the curable film-forming composition to a substrate. For example, the packages may be combined less than 8 hours prior to application, or less than 4 hours prior to application, or less than 2 hours prior to application, or less than one hour prior to application, or less than 30 minutes prior to application. [0060] Suitable catalytic materials that catalyze a chemical reaction between hydroxyl and anhydride functional groups include any of those known in the art; in particular, pyridine, dimethylaminopyridine, 1 ,4-diazabicyclo[2.2.2]octane, 1 ,5,7-triazabicyclo[4.4.0]dec-5-ene, dimethylethanolamine, dimethylcocoamine, phosphines, phosphonium and/or ammonium salts of organic acids such as phosphonium acetates, Lewis acids, and the like. In certain examples, the composition is substantially free, essentially free, or completely free of triethylene diamine, bis(2-dimethyl aminoethyl)ether, and N,N,N1 , N 1 -tetramethylethylenediamine.

[0061] The curable film-forming compositions disclosed herein may be used to prepare a coated substrate, comprising: 1 ) a substrate having at least one coatable surface, and 2) a cured film-forming composition on at least one surface of the substrate, wherein the cured film-forming composition is formed from any of the curable film-forming compositions described above.

[0062] The curable film-forming composition may also be used in a method for forming a coated substrate. The method comprises:

(A) optionally applying a primary film-forming composition to at least a portion of a surface of the substrate to form a first coating; (B) applying any of the curable film-forming compositions described above directly to at least a portion of a surface of the substrate or to at least a portion of the first coating formed in step (A) to form a coated substrate; and

(C) subjecting the coated substrate to curing conditions whereby the curable film-forming composition undergoes multiple cure reactions as described above.

[0063] Suitable substrates include rigid metal substrates such as ferrous metals, aluminum, aluminum alloys, copper, and other metal and alloy substrates. The ferrous metal substrates may include iron, steel, and alloys thereof. Non-limiting examples of useful steel materials include cold rolled steel, galvanized (zinc coated) steel, electrogalvanized steel, stainless steel, pickled steel, zinc-iron alloy such as GALVANNEAL, and combinations thereof. Combinations or composites of ferrous and non-ferrous metals can also be used. In certain examples, the substrate comprises a composite material such as a plastic or a fiberglass composite. Often the substrates are used in turbines and aircraft parts such as airfoils, wings, stabilizers, rudders, ailerons, engine inlets, propellers, rotors, fuselage and the like. The substrates may also be used in vehicle components such as wheels, bumpers, fenders, hoods, doors, panels, etc., on automobiles, trucks, watercraft, and the like; or on construction equipment, building structures such as corrugated metal walls or roofing, wind blades, bridge supports, or other outdoor structures.

[0064] Other suitable substrates include any that are transparent. The term “transparent”, as used for example in connection with a substrate, film, material and/or coating, means that the indicated substrate, coating, film and/or material has the property of transmitting light without appreciable scattering so that objects lying beyond are entirely visible. A transparent article typically exhibits a haze value of less than 3 percent, e.g., less than 1 percent or less than 0.5 percent, when the haze value is measured by, for example, a Haze Gard Plus Instrument. For example, the curable film-forming compositions may be applied over optical substrates known in the art, including non-plastic substrates such as glass. Suitable examples of optical plastic substrates include polyol(allyl carbonate), e.g., allyl diglycol carbonates such as diethylene glycol bis(allyl carbonate), which is sold under the trademark CR-39 by PPG; polyurea- polyurethane (polyurea urethane) polymers, which are prepared, for example, by the reaction of a polyurethane prepolymer and a diamine curing agent, a composition for one such polymer being sold under the trademark TRIVEX® by PPG; polyol(meth)acryloyl terminated carbonate monomers; diethylene glycol dimethacrylate monomers; ethoxylated phenol methacrylate monomers; diisopropenyl benzene monomers; ethoxylated trimethylol propane triacrylate monomers; ethylene glycol bismethacrylate monomers; polyethylene glycol) bismethacrylate monomers; urethane acrylate monomers; poly(ethoxylated Bisphenol A dimethacrylate); poly(vinyl acetate); poly(vinyl alcohol); poly(vinyl chloride); poly(vinylidene chloride); polyethylene; polypropylene; polyurethanes; polythiourethanes; thermoplastic polycarbonates, such as the carbonate-linked resin derived from Bisphenol A and phosgene, one such material being sold under the trademark LEXAN, available from A&C Plastics, Inc.; polyesters, such as the material sold under the trademark MYLAR, available from DuPont Teijin Films; polyethylene terephthalate); polyvinyl butyral; poly(methyl methacrylate); and polymers prepared by reacting polyfunctional isocyanates with polythiols or polyepisulfide monomers, either homopolymerized or co-and/or terpolymerized with polythiols, polyisocyanates, polyisothiocyanates and optionally ethylenically unsaturated monomers or halogenated aromatic-containing vinyl monomers. Also suitable are copolymers of such monomers and blends of the described polymers and copolymers with other polymers, e.g., to form interpenetrating network products. Such optical substrates may be used as lenses, screens, or covers (for transmitters, receivers, and the like) on components of autonomous vehicles.

[0065] Before depositing any coating compositions upon the surface of the substrate, it is common practice, though not necessary, to remove foreign matter from the surface by thoroughly cleaning and degreasing the surface. Such cleaning typically takes place after forming the substrate (stamping, welding, etc.) into an end-use shape. The surface of the substrate can be cleaned by physical or chemical means, such as mechanically abrading the surface or cleaning/degreasing with commercially available alkaline or acidic cleaning agents which are well known to those skilled in the art, such as sodium metasilicate and sodium hydroxide. A non-limiting example of a cleaning agent is CHEMKLEEN 163, an alkaline-based cleaner commercially available from PPG Industries, Inc.

[0066] Following the cleaning step, the substrate may be rinsed with deionized water, with a solvent, or an aqueous solution of rinsing agents in order to remove any residue. The substrate can be air dried, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature (e. g., 40 to 80 °C), or by passing the substrate between squeegee rolls.

[0067] The substrate may be a bare, cleaned surface; it may be oily, or pretreated with one or more pretreatment compositions. The surface of the substrate may be further prepared by sanding or other conventional preparation processes. Optionally in step (A), at least a portion of a surface of the substrate may be coated with one or more primary film-forming compositions such as electrocoats, primers, surfacers, topcoats including pigmented basecoats, etc., applied by any method including, but not limited to, electrodeposition, spraying, dip coating, roll coating, curtain coating, and the like, to form a first coating.

[0068] The composition described above may be applied directly to at least a portion of a surface of the substrate (e. g., “direct-to-metal”) or to at least a portion of the first coating if applied as step (A), by one or more of a number of methods including spraying, dipping/immersion, brushing, or flow coating. They are most often applied by spraying. The usual spray techniques and equipment for air spraying and electrostatic spraying and either manual or automatic methods can be used. The coating layer typically has a dry film thickness of 1 - 25 mils (25.4-635 microns), often 2-15 mils (50-381 microns).

[0069] Suitable electrocoat compositions for use as a primary film-forming composition include ED 6465; primers include HP78224EH, both commercially available from PPG. Alternatively, a primer may not be used and the filmforming compositions can be applied directly to a pigmented basecoat or other coating. Multiple coating layers such as an electrocoat and a primer and optionally a colored base coat may be applied to the substrate prior to application of the curable film-forming composition described above. The curable film-forming compositions used in step (B) above are often used as clear coats in an automotive OEM or refinish setting. [0070] After forming a film of the coating on the substrate, the composition can be cured, usually by subjecting it to a temperature of at least 35°C, or at least 100°C, or at least 125°C, to at most 250°C, or at most 200°C, or at most 150°C. Exemplary temperature ranges include 35-250°C, 35-200°C, 35-150°C, 100- 250°C, 100-200°C, 100-150°C, 125-250°C, 125-200°C, and 125-150°C. In some instances, the composition may be cured at low temperatures; i. e., by subjecting it to a temperature below 80°C, or in a range of 0-80°C; or below 35°C, or in a range of 10-35°C; such as at ambient temperature (for example, a typical room temperature, 72°F (22.2°C)). Such a cure regimen may be suitable for a multi-package composition that includes a catalytic material, which can effect or facilitate a reaction below 35°C. The composition may be cured at ambient temperature typically for at least one hour, or at least 5 hours, or at least 24 hours, such as in a period ranging from about one hour to several weeks, or from about 24 hours to several days, or from about 24 hours to about 36 hours. A combination of ambient temperature cure and baking may be used to cure the composition, or baking alone. If ambient temperature and baking are utilized in combination, the composition is often allowed to stand (“flash”) for a period of from about 2 minutes to about 120 minutes at a temperature ranging from ambient to 175°F (79.4°C), followed by baking at a temperature up to about 300°F (148.9°C), usually 285°F (140.6°C) for a period of time ranging from about 20 minutes to about 1 hour.

[0071] After application of the curable film-forming composition to a substrate to form a coated substrate, and upon subjecting the coated substrate to curing conditions, the curable film-forming composition typically undergoes multiple (i. e., more than one different) cure reactions, including any of those disclosed above. The curable film-forming compositions used to form the coated substrates undergo isocyanate-free cure chemistries, and may proceed at ambient conditions to yield coatings with properties comparable to polyurethane coatings.

[0072] The following working Examples are intended to further describe and demonstrate the compositions and coated substrates described herein. It is understood that the disclosure of this specification is not necessarily limited to the examples described in this section. Components that are mentioned elsewhere in the specification as suitable alternative materials for use, but which are not demonstrated in the working Examples below, are expected to provide results comparable to their demonstrated counterparts. Unless otherwise indicated, all parts are by weight.

EXAMPLES

Abbreviations

TRIGONOX 131 = tert-amylperoxy 2-ethylhexyl carbonate, available from AkzoNobel Functional Chemicals

TRIGONOX 21 = t-butyl peroctoate, available from AkzoNobel Functional Chemicals

BA = butyl acrylate

MMA = methyl methacrylate

4-HBA = 4-hydroxybutyl acrylate

BMA = butyl methacrylate

STY = styrene

[0073] Various resins for use in the preparation of curable film-forming compositions were prepared as shown in the Synthesis examples below.

Synthesis Example A: Hydroxybutylacrylate Polyol

[0074] In a four neck round bottom flask, 409.5 grams of butyl acetate (BuAc) was added and the flask was set up with a mechanical stir blade, thermocouple, and reflux condenser. The flask containing BuAc solvent was heated to a set point of 130 °C under a nitrogen atmosphere. A monomer solution containing 315.0 grams of MMA, 262.5 grams of 4-HBA, 105.0 grams of BA, 157.5 grams of STY, and 210.0 grams of BMA was thoroughly mixed in a separate container. A solution of 52.5 grams of TRIGONOX 131 and 147.0 grams of BuAc was prepared and added into the flask over 190 minutes through an initiator addition funnel. Ten minutes after the initiator solution feed started, the monomer solution feed was started and added over 180 minutes through a monomer addition funnel. After both initiator and monomer feeds were complete, the monomer addition funnel was rinsed with 42.0 grams of BuAc. The reaction was then held at 130 °C for 60 minutes. Then another solution of 5.5 grams of TRIGONOX 131 and 15.8 grams of BuAc was added over 30 minutes through the initiator addition funnel. After this second initiator feed was complete, the initiator addition funnel was rinsed with 42.0 grams of BuAc. The reaction was then held at 130 °C for 60 minutes. After the 60 minute hold, the reaction was cooled and poured into a suitable container. The final measured solids content of the resin was determined to be 63.17 % solids.

Synthesis Example B: Carbodiimide

[0075] In a four neck round bottom flask, 385.7 grams of 4,4’-methylene dicyclohexyl diisocyanate and 2.87 grams of 1 -methyl-2,3-dihydrophosphole 1 - oxide was added and the flask was set up with a mechanical stir blade, thermocouple, and reflux condenser. The flask was heated to a set point of 160 °C under a nitrogen sparge. The reaction mixture was held at 160 °C until the measured isocyanate equivalent weight of the mixture reached 328 grams/equivalent, at this time the mixture was cooled to 60 °C and the reaction mixture was no longer sparged with nitrogen. During this period of cooling 108.1 grams of butyl acetate was added to the flask. Once the mixture reached 60 °C, 106.4 grams of dibutylamine was added over 60 minutes through an addition funnel. The funnel was rinsed with 9.8 grams of butyl acetate and the reaction mixture was held at 70°C until the peak corresponding to the isocyanate group disappeared by infrared spectroscopy. The final measured solids of the resin was determined to be 79.62 % solids.

Synthesis Example C: Maleic Anhydride Copolymer

[0076] In a four neck round bottom flask, 106.6 grams of ethyl-3- ethoxypropionate (EEP) and 82.3 grams of butyl acetate (BuAc) was added and the flask was set up with a mechanical stir blade, thermocouple, and reflux condenser. The flask containing EEP and BuAc solvents was heated to a set point of 150 °C under a nitrogen atmosphere. A monomer solution containing 98.4 grams of EEP, 98.4 grams of BuAc, 56.8 grams of MMA, 1 13.6 grams of maleic anhydride, 227.1 grams of STY, and 170.3 grams of BA was thoroughly mixed in a suitable container until the maleic anhydride was fully dissolved. A solution of 79.5 grams of TRIGONOX 21 and 39.6 grams of EEP was prepared and added into the flask over 190 minutes through an initiator addition funnel. Ten minutes after the initiator solution started, the monomer solution was started and added over 180 minutes through a monomer addition funnel. After both initiator and monomer feeds were complete, the monomer addition funnel was rinsed with 6.6 grams of EEP and 8.1 grams of BuAc. Then another solution of 5.5 grams of TRIGONOX 21 and 21 .9 grams of EEP was added over 30 minutes through the initiator addition funnel. After this second initiator feed was complete, the initiator addition funnel was rinsed with 15.2 grams of BuAc. The reaction was then held at 150 °C for 60 minutes. After the 60 minute hold, the reaction was cooled and poured into a suitable container. The final measured solids content of the resin was determined to be 54.84 % solids.

[0077] Curable film-forming compositions of the present disclosure and of a comparative nature were prepared as shown in the examples below. Methods for forming a coated substrate in accordance with the present disclosure are also demonstrated in the Examples below.

[0078] The following Examples illustrate the curing of a hydroxyl-containing compound with an anhydride-containing component and an aziridine containing component. The composition of Comparative Examples I and VI do not contain an aziridine functional compound. In each of Examples II to V, VII and VIII, polyol, aziridine, and solvent were mixed, then anhydride and catalyst were added, and solutions were homogenized. Solutions were drawn down on sanded and solvent-wiped POWERCRON 8000 cold-rolled steel panels (available from ACT Test Panels LLC) with a 10 mil gap drawdown bar, and allowed to cure at ambient conditions. Methyl ethyl ketone (MEK) resistance were measured after 24 hours. MEK resistance was determined by a modified version of ASTM D5402-19 using an MEK-saturated Kimberly Clark Professional Wypall X80. Tack free time was determined as the approximate time at which the coating could be touched lightly without any adhering to the finger. Gel time was determined as the time at which the container of paint could be inverted with no observable flow in ca. 30s. Konig Hardness was determined using a BYK Pendulum Hardness Tester in accordance with ASTM D4366-16. DOI (distinctness of image) and 60° gloss values were determined using a Rhopoint DOI/Haze/Glossmeter.

[0079] The data from the table above demonstrate that compositions comprising a hydroxyl functional compound, an anhydride functional compound, and an aziridine functional compound give coatings that cure under ambient conditions. The data further demonstrates that properties of the coatings can be adjusted by component selection and relative stoichiometry.

[0080] The data from the table above demonstrate that pigmented compositions comprising a hydroxyl functional compound, an anhydride functional compound, and an aziridine functional compound cure at ambient conditions. Furthermore, the results demonstrate that the inventive compositions show properties comparable to a commercial isocyanate-cured coating systems.

[0081] The following examples were prepared and tested as above demonstrating the curing of an anhydride-functional component and an aziridine functional component. The anhydride-functional component, aziridine- functional component, and solvent were mixed, the catalyst and optionally water were added, the solutions were homogenized, then the samples were applied via drawdown with a 10 mil gap drawdown bar.

[0082] The data from the table above demonstrate that compositions comprising an anhydride-functional component and an aziridine functional component provide coatings the can be cured under ambient conditions.

[0083] Whereas particular embodiments of this disclosure have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present disclosure may be made without departing from the scope thereof as defined in the appended claims.

Claims

Therefore, we claim:

1 . A non-aqueous, curable film-forming composition comprising:

(a) an anhydride functional compound;

(b) an aziridine functional compound; and

(c) a hydroxyl functional compound different from (a) and (b) and having at least two hydroxyl functional groups.

2. The curable film-forming composition of claim 1 , further comprising hydrolyzable functional groups different from anhydride that are present on at least one of the anhydride functional compound (a), the aziridine functional compound (b), the hydroxyl functional compound (c), and a separate compound that is different from the anhydride functional compound (a), the aziridine functional compound (b), and the hydroxyl functional compound (c).

3. The curable film-forming composition of claim 1 or 2, wherein the hydrolyzable functional groups comprise alkoxysilane, acetoxysilane, ketoxime silane, silicate, titanate, and/or zirconate functional groups.

4. The curable film-forming composition of claim 2 or 3, wherein the hydroxyl functional compound (c) further comprises the hydrolyzable functional groups.

5. The curable film-forming composition of any of claims 2 to 4, wherein the anhydride functional compound (a) further comprises the hydrolyzable functional groups.

6. The curable film-forming composition of any of claims 2 to 5, wherein the aziridine functional compound (b) further comprises the hydrolyzable functional groups.

7. The curable film-forming composition of any of claims 2 to 6, wherein the hydrolyzable functional groups are present on the separate compound.

8. The curable film-forming composition of claim 7 , wherein the separate compound having hydrolyzable functional groups comprises an acrylic polymer having silane functional groups.

9. The curable film-forming composition of claim 7 , wherein the separate compound having hydrolyzable functional groups comprises urethane and/or urea linkages.

10. The curable film-forming composition of any of claims 1 to 9, wherein the anhydride functional compound (a) comprises at least one of an anhydride-containing polymer, maleic anhydride, hexahydrophthalic anhydride, succinic anhydride, a (3-trialkoxysilyl)propyl succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methyl hexahydrophthalic anhydride and methyl succinic anhydride.

1 1. The curable film-forming composition of any of claims 1 to 10, wherein the curable film-forming composition comprises separate packages, wherein a first package comprises the anhydride functional compound (a) and wherein a second package comprises the hydroxyl functional compound (c); and wherein the aziridine functional compound (b) is present in the first and/or second package; and wherein the curable film-forming composition further comprises a catalytic material (d) that catalyzes a chemical reaction between hydroxyl and anhydride functional groups; and wherein the packages are separate from one another until immediately prior to application of the curable film-forming composition to a substrate.

12. The curable film-forming composition of any of claims 1 to 1 1 , wherein after application of the curable film-forming composition to a substrate to form a coated substrate, and upon subjecting the coated substrate to curing conditions, the curable film-forming composition undergoes multiple cure reactions.

13. A method for forming a coated substrate comprising: (A) optionally applying a primary film-forming composition to at least a portion of a surface of the substrate to form a first coating;

(B) applying the curable film-forming composition of any of claims 1 to 12 directly to at least a portion of a surface of the substrate or to at least a portion of the first coating formed in step (A) to form a coated substrate; and

(C) subjecting the coated substrate to curing conditions whereby the curable film-forming composition undergoes multiple cure reactions.

14. The method of claim 13, wherein the primary film-forming composition is applied to at least a portion of a surface of the substrate and comprises an electrocoat, a primer, a surfacer, and/or a topcoat.

15. The method of any of claims 13 to 14, wherein the coated substrate is subjected to a temperature of 35°C to 250°C to effect curing.

16. The method of any of claims 13 to 14, wherein the curable filmforming composition undergoes the cure reactions at a temperature below 35°C.

17. A coated substrate formed by any of the methods of claims 13 to

16.